1.4: Demonstration - Comparing heat capacity

This course introduces a number of basic scientific principles underpinning the methodology of cooking, food preparation and the enjoyment of food. All topics covered have a strong basis in biology, chemistry, and physics application. Among others, they include the consumption of cooked food, the physiological and evolutionary implication of the senses, geographic and cultural influences on food, and the rationale behind food preparation. We will also discuss issues such as coupling of senses to improve sense stimulation; altering flavor by chemical means; and modification of the coloration to improve the appearance of dishes. Following the video demonstrations of the scientific principles of cooking, you will learn to recognize the key ingredients and their combinations for preparing good healthy food. At the end of this course, you will be able to:
- appreciate the scientific basis of various recipes;
- develop your own recipes by integrating some of the scientific principles into new dishes;
- recognize the influence of the material world on human perception from the different senses;
- appreciate the art of integrating science into cooking and dining.
Important Note: This course is not designed for people with special dietary needs such as vegetarian, diabetic, and gluten-free diets. If you feel uncomfortable with any part of the assignments or activities of this course, you can substitute some of the ingredients or ask friends and family members to help with the tasting of your assignments. Alternatively, you may skip that specific assignment provided that you have fulfilled all other qualifying requirement to pass the course.
Course Overview video: https://youtu.be/H5vlaR0_X2I

AJ

there should be a digital certificate in PDF for those who can not pay because everybody does a lot of effort and time to finish this course

JA

Nov 20, 2017

Filled StarFilled StarFilled StarFilled StarFilled Star

It was vary good gave me ideas on how to improve my cooking technique, and allowed me to use my imagination to make my dishes better!

从本节课中

Orientation, Module 1 and Module 2

This week, we will focus on “Energy Transfer” and “Hunger and Satiety”. Before you start with the content for these modules, please watch the Course Overview, review the Grading Scheme, and read the Important Note on special dietary needs.

教学方

King L. Chow

Professor

Lam Lung Yeung

Associate Professor

脚本

In this demonstration, we're trying to show you what heat capacity is really about. When we talk about heat capacity we are referring to a body of material, and if you want to change the temperature of this fixed body of material for a fixed amount of temperature, how much energy is required? For example, for a material which takes a lot of energy to raise the temperature for this fixed amount, it has a high heat capacity. But, for another body which takes in less energy to generate the same temperature change, that has a lower heat capacity. So let's demonstrate and see how it can be visualized. So what we have here is two body of liquid. On my left it is 100 grams of water, and on my right is 100 grams of oil. Now, because of the difference of density you may see that oil has a slightly larger volume, but that's fine because it's fixed amount and fixed mass. Now what we're going to do is we look at initially what the temperature of these two bodies are. Both of them right now is roughly about 23.3, 23.4 degree Celsius. Now, so we are going to transfer some energy into it. How do we do it? We are going to have on my right hand side a heating block that heated up two metal blocks to 80 degree. Now what I have done when I transfer this metal block into this body of liquid, the heat will be dissipated into this body of liquid. And as a result, the temperature of this body of liquid is going to increase. But depending on the heat capacity of this material, they're going to have a different degree of change of temperature. Now let's see what happens. Now it's 80 degrees, so it's a little bit hot, so I need to use the gloves to carry it. Now, here it goes. Now, I transfer this metal block into water. Okay. So I shake it a little bit. And then I transfer another metal block into the oil. Okay. And then I shake it a little bit. Now, it may take awhile that having these two body of metal block put into the liquid, heat will be dissipated. And it takes awhile for them to go through the process of equilibration, so I need to stir them a little bit and see how the temperature is going to be changed. Okay, now let's look at the temperature. Okay, now both of them actually has a temperature increase. Let's wait a while and see how the temperature continue to change. So we continue to stir it a little bit to make sure that it reaches equilibrium. After a while, so the equilibrium has been reached. So let's look at the temperature again. So, for the body of water now is about 28 degree, 27.9. And for the oil, the temperature is 31, 31.1. So that's a big difference in terms of temperature. So what it tells us is that water, with high heat capacity, it takes in the same amount of energy, but the temperature change would be less compared with the oil, which has lower heat capacity. The same energy results in a higher difference of temperature.